Progressive, Stativeand Dynamic Verbs

The progressive forms of a verb indicate that something is happening or was happening or will be happening. When used with the past, the progressive form shows the limited duration of an event: "While I was doing my homework, my brother came into my room." The past progressive also suggests that an action in the past was not entirely finished. (Compare "I did my homework." to "I was doing my homework.") This is even more evident in the passive progressive construction: "He was being strangled in the alley" suggests an action that was not finished, perhaps because the act was interrupted by a good citizen, whereas the simple past "He was strangled in the alley" suggests an action that was finished, unfortunately.

A neat categorization of the uses of the progressive can be found on the page describing the "To Be" Verb.

Transitional Events Verbs
Progressive forms indicate the beginning of an event,
as opposed to the simple present tense.
"She was falling out of bed [when I caught her]" as opposed to
"She falls out of bed every night."

arrivedie

fallland

leave

lose

Momentary Verbs
Progressive forms indicate little duration and suggest repetition.
She is hitting her brother.
He is jumping around the house.

hitjump

kickknock

nod

tap

STATIVE VERBS

Verbs of Inert Perception and Cognition*
I detest rudabaga, but not I am detesting rudabaga.
I prefer cinnamon toast, but not I am preferring cinnamon toast.